I think the trial should last for 30 days, but I don't know that for sure. Try trashing your preferences file. Here's a link to a long page of instructions in English, but try the suggestion in the second paragraph first.
Credo cheil processo dovrebbedurare 30giorni, maionon lo soper certo.Provare acestinareil filedelle preferenze. Ecco un linkaduna lungapaginadiistruzioni in inglese, ma provateil suggerimentoal secondo commaprimo.